Odd observation about heating elements

Discussion in 'General Electronics Chat' started by electronis whiz, Oct 11, 2015.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    I have an old hairdryer I had for doing heatshrink, etc. It seemed maybe the fan was starting to fail and I wanted one with a non-heat function too for blowing dust so I replaced it. I decided to have some fun with the old one just to see what changing the air intake opening size would do. I had it on high I covered up a large chunk of the air intake and noticed the elements glowed red. Then I let the inlets open completely and it went dark. I noticed though near the areas where the wire bends around the center form it still glows a faint red where it never did before.

    I'm now kind of curious why a small portion of wire went from never glowing before to glowing after this. My only guess is that is like a weak point and the wire stretched perhaps or had some kind of oxidation or chemical change at a temp where this wire will glow.
  2. Glenn Holland

    Active Member

    Dec 26, 2014
    A kink in the wire will probably be higher resistance and create a hot spot.
  3. #12


    Nov 30, 2010
    The center support restricts air flow more than a completely open tube restricts air flow. There is a laminar surface flow around the obstruction.
  4. DickCappels


    Aug 21, 2008
    If it wasn't a mechanical of chemical change resulting from elevated temperature as you propose, it might be that the case that those sections always glowed faintly red but until your experiment you were not interested enough to notice it.